A former Barclays trader who was jailed for rigging the Libor rate has lost his appeal against his conviction.
Jailing Alex Pabon for two years and nine months in July 2016 after he was found guilty with others of conspiracy to defraud, a judge at Southwark Crown Court said the fraud had hit the "integrity of the market".
Lawyers for Pabon, 39, who has since been released and lives in the US, said that his conviction was unsafe because the conduct of expert witness Saul Haydon Rowe fell far below the standards expected.
Rowe's failings included secretly consulting with a number of undisclosed advisers, blatantly disregarding a judge's directions and knowingly giving evidence about matters outside his area of competence, Pabon's counsel Tom Allen QC said.
While accepting that Rowe had not complied with his duties, the Serious Fraud Office (SFO) said that there was no live issue pursued by the prosecution arising from his evidence, which was the "uncontroversial backdrop to the case".
At the Court of Appeal on Tuesday, three judges said that while Rowe signally failed to comply with his basic duties, he did not impact "at all or sufficiently" on the key issue in the trial - Pabon's alleged dishonesty - so as to affect the safety of the conviction.
Lord Justice Gross said that the instruction of Rowe turned into an "embarrassing debacle" for the SFO.
"All the more so, given the high-profile nature of these cases and notwithstanding that, in the event, it has had no impact on the outcome in this case."
He added that the SFO had told the court that extensive internal discussions resulted in the conclusion that Rowe's conduct "resulted from a failure of integrity on his part rather than a failure of SFO policies or procedures".
The SFO undertook to look again at the matter to see whether there was any way in which it could reinforce expert witnesses' awareness of their obligations, said Lord Justice Gross.
"In fairness to the SFO, this was the third time that Rowe had given evidence in Libor trials and the first time any questions concerning his expertise has apparently arisen.
"Nonetheless, there is no room for complacency and this case stands as a stark reminder of the need for those instructing expert witnesses to satisfy themselves as to witness expertise and to engage - difficult though it sometimes may be - an expert of a suitable calibre."